Control system for rotary duplicating machines



Feb. 24, 1953 T. F. ESERKALN CONTROL SYSTEM FOR ROTARY DUPLICATING MACHINES 11 Sheets-Sheet 1 Filed May 20, 1949 Feb. 24, 1953 T. F. ESERKALN 2,629,844

CONTROL SYSTEM FOR ROTARY DUPLICATING MACHINES Filed May 20, 1949 11 Sheets-Sheet 2 I N VEN TOR.

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CONTROL SYSTEM FOR ROTARY DUPLICATING MACHINES Filed May 20, 1949 ll Sheets-Sheet 4 Feb. 24, 1953 T. F. ESERKALN CONTROL SYSTEM FOR ROTARY DUPLICATING MACHINES Filed May 20, 1949 INVENTOR ll Sheets-Sheet 5 9 Feb. 24, 1953 T. F. ESERKALN 2,629,844

CONTROL SYSTEM FOR ROTARY DUPLICATING MACHINES Filed May 20, 1949 11 Sheets-Sheet e INVENTOR.'.

Feb. 24, 1953 T. F. ESERKALN CONTROL SYSTEM FOR ROTARY DUPLICATING MACHINES Filed May 20, 1949 ll Sheets-Sheet '7 T INVENTOR.

Feb. 24, 1953 T. F. ESERKALN 2,629,844

CONTROL SYSTEM FOR ROTARY DUPLICATING MACHINES Filed May 20, 1949 ll Sheets-Sheet 8 I N VEN TOR.

Feb. 24, 1953 T. F. ESERKALN CONTROL SYSTEM FOR ROTARY DUPLICATING MACHINES 11 Sheets-Sheet 9 Filed May 20, 1949 i I (F1 N VEN TOR.

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CONTROL SYSTEM FOR ROTARY DUPLICATING MACHINES Filed May 20, 1949 ll Sheets-Sheet l0 F201] 1cm) 7 6' i o 91 WURK SF'INDLE DRIVE.

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a RW NBQ mun MERN nwwm a NNQN @200 Feb. 24, 1953 Filed May 20, 1949 DUNN Patented Feb. 24, 1953 CONTROL SYSTEM FOR ROTARY DUPLICATING MACHINES Theodore F. Eserkaln, Wauwatosa, Wis., assignor to George Gorton Machine 00., Racine, Wis., a corporation of Wisconsin Application May 20, 1949, Serial No. 94,390

8 Claims.

This invention relates to certain improvements in control system for rotary duplicating machines and the like, and particularly such machines designed for efiiciently machining to finished form articles of irregular contours; and the nature and objects of the invention will be readily recognized and understood by those skilled in the arts to which the invention relates in the light of the following explanation and detailed description of the accompanying drawings illustrating what I at present consider to be a preferred form and embodiment of control system of my invention, from among various other forms, embodiments, designs and arrangements thereof, and of constructions, combinations and subcom binations of elements making up such a system. of which the invention is capable within the spirit and scope thereof as defined by the claims hereinafter appended.

My invention is primarily directed to the problem of manufacturing by milling, grinding or other material removin or finishing methods from work pieces or blanks, various articles havin external shapes of irregular contours axially therealong and/or radially therearound, such as typified by turbine blades, vanes and the like articles, characterized by a large thickness to width or chord ratio, so that, a cross section of such an article at stations along its major length presents a thin section shape or contour lying within a generally rectangular area having a large thickness to width ratio, that is to say, of a generally flat rectangular shape in cross section. While the invention is not limited or restricted to the production by such methods of such articles as turbine blades, compressor vanes, buckets and the like, it is particularly adapted thereto because the conditions and problems to the solution of which the invention is directed, are met with to an accentuated degree in the production of such articles by automatic or semi-automatic power driven machines.

A machine of my invention for producing articles of irregular contours from a work piece by pattern controlled material removal from the work piece has been selected as exemplifying certain of the problems to the solution of which a control system of my present invention is directed. In this type of machine the work piece is revolved and the material removing tool is moved toward and from the work piece while being maintained in material removingengagement therewith under the control of a pattern and while being fed in one direction axially along the work piece. In order to efficiently and accurately machine the work piece to the contours of the pattern it is necessary to control the rate of rotation of the work piece relative to the rate or velocity of radial in and out movements of the tool as well as to control the rate of feed movement of the tool axially along the work piece if the particular article being machined from the work piece requires the latter movement.

It is therefore one of the objects of the invention to provide for automatic and precise control of the rate of speed of revolution of the work piece in direct proportion to the rate of movements radially inwardly or outwardly of the tool from any at rest position thereof, toward or from the work piece, to effect a slow down or reduction in the rate of revolution of the work piece upon movement of the tool either inwardly or outwardly, and to restore instantly the maximum speed of rotation of the work piece when the tool comes to rest in any position thereof radially relative to the work piece.

Another object is to revolve the work piece and to feed the tracer and tool axially of the work piece simultaneously from a common power source under the control automatically of the movements of the tracer and tool unit either in a direction toward or a direction away from the work piece, to cause said common power source to effect simultaneously a slow down or reduction of the rate of revolution of the work piece and of the rate of linear feed of the tool, irrespective of the direction but in direct proportion to the rate of such in and out movements.

It is a further object to provide a highly accurate and sensitive electronic control system or network for controlling the power source for revolving the work piece and for feeding the tracer and tool unit, to eiiect slow-down or reduction in the rate of revolution of the work piece and correlated rate of linear speed of the tool in direct proportion to the rate of movement or velocity of the tool in or out relative to the work piece as dictated by the pattern contour.

Another object is to provide a direct current electrical motor as the common power source for revolving the workpiece and feeding the tool and tracer therealong, together with an electronic control system which includes grid-biased, gaseous power tubes for controlling the rate of speed of such motor, with the control of the grids of such power tubes effected by signals in the form of an electrical potential or voltage imposed on and tool in or out relative to a work piece and to restore such electronic system to normal condition for maximum speed of operation of the motor with maximum rate of revolution of the work piece and feed of the tracer and tool when the tool is at rest radially or in directions in or out relative to a work piece.

Another object is to provide an electrical instrumentality for generating a signal by movements of the tool toward or from, i. e. in or out relative to the work piece, in the form of an electrical potential or voltage of a magnitude in direct proportion to the rate of any such movements for causing operation of the electronic system to effect a slow down in the rate of speed of the work revolving and feeding motor in direct proportion to the magnitude of the generated signal.

And a further object is to provide such a signal generator in the form of a coil electrically connected into the electronic control system, and a permanent magnet, with the magnet and coil mounted for current generating movements relative to each other by movements of the tracer and tool unit toward and from a work piece, for generating by such relative movements the signal potential or voltage for operating the electronic control circuits.

It is another object to provide such an electronic control system or network for controlling the rate of speed of the motor for revolving the work piece and feeding the tool therealong, in which the inertia of the motor following a slow down or speed reduction thereof, is effectively braked electrically to thereby instantly bring the motor to the lower rate of speed without appreciable lag or time delay.

With the foregoing and various other objects, features and results in view which will be apparent from the following detailed description and explanation, my invention consists in certain novel combinations and arrangements of parts, elements and organizations, and in the design and construction thereof, all as will be more fully an particularly referred to and specified hereinafter.

Referring to the accompanying drawings in which similar reference characters refer to corresponding parts and elements throughout the several figures thereof:

Fig. 1 is a perspective view taken from the front of a rotary duplicating machine of my invention, showing a turbine blade blank m unted therein for automatic pattern controlled machining of the blade to completed form.

F g. 2 is a view in front elevation of the ma ch ne of Fig. 1, certa n elements of the work spindle drive and saddle and carriage unit feed an rapid traverse be ng shown in dotted lines.

Fig. 3 is a view in front elevation of the machine of Fig. 2 w th the saddle and carriage unit removed. a portion of the machine frame structure bein shown in vertical section to disclose certain of the gear trains and clutches of the feed and rapid traverse drive transmissions.

F g. 4 is a vertical transverse section through the feed and rap d traverse drive transmissions, taken as on the line 4-4 of Fig. 2.

F g, a horizontal sectional view taken as on the line Ilaa of Fig. 4 and showing in top plan the shiftable clutch actuators and associated. operating mechanisms.

5 is a view in elevation of the right hand end of the machine of Fig. 1, showing particularly the pull-back cylinder air controlling valve unit, the control mechanism therefor, and the lines thereto.

Fig. 6 is a horizontal section taken as on the line 6-6 of Fig. 5, showing particularly the anti-friction slide mounting of the cross feed carriage on the saddle and the feed clutch for the saddle and carriage unit feed screw.

Fig. '7 is a transverse, vertical section taken as on the line 1-1 of Fig. 2.

Fig. 8 is a vertical transverse section taken as on the line 8-8 of Fig. 2, and showing particularly the work spindle and its drive and the construction of one of the cross feed carriage spring loading units.

Fig. 9 is a top plan View showing the feed control rod and rapid traverse clutch control rod and associated mechanisms at the opposite ends thereof, respectively.

Fig. 10 is a purely schematic view shOWing the relationships between the peripheral pattern surface of the master cam and the contour of the finished article from which generated, with the tracer roller and cutter, respectively.

Figs. 11, 12 and 13, are diagrammatic views illustrating by vector diagrams the variations in the magnitude of the velocity of movement of a contour surface of a revolving work piece past the point of cutting engagement therewith of a material removing tool in different locations around the contour of the work piece when the speed of the rotation of the work piece is not correlated with the velocity of radial movements of the tool toward and from the work piece.

Figs. 14 and 15 are diagrammatic views illustrating by vector diagrams the maintenance of constant velocity of movement of the contour surface of the revolving work piece past the point of material removing engagement therewith of the tool by the control provided by the invention.

Fig. 16 is a schematic diagram of the circuits and associated electrical elements constituting the spindle motor electronic speed controlling and braking network.

Fig. 17 is a schematic diagram of the power circuits for the cutter spindle and rapid traverse motors, and for the rapid traverse clutch, feed clutch and air cylinder control valve actuating solenoids.

Fig. 18 is a schematic diagram of the control circuits for the power circuits of Fig. 1'7.

Fig. 19 is a vertical section taken through the signal generating magnet and coil unit.

Fig. 20 is a bottom plan view of the signal generating magnet and coil unit.

A machine organization has been selected and is illustrated and described herein by way of example as of a type in which the work piece or blank to be machined is positioned and mounted for rotation about a horizontally disposed axis, with the cutting tool pattern controlled for cross feeding toward and from the work piece or blank in either direction along a straight line path disposed radially of and. passing through the axis of revolution of the work piece. However, it is to be understood that the control system and the combination thereof with the components of a machine of the invention are not limited to adaptation to the particular machine organization of the example having such relative positioning of the work piece and cutter, as the invention contemplates and includes adaptations to and co binations with machine organizations in which the work .piece may be revolved about a vertically or angularly disposed axis with the cutting tool cross fed under the control of the pattern, inwardly and outwardly relative to the work piece along a path disposed radially of and relative to such a vertical or angular axis of work piece revolution.

The illustrated example machine organization of the invention, referring now to Figs. 1, 2, 3 and 5, in particular, includes a main frame structure i which may be in the form of a single casting, or may be built-up from separate elements or components to provide a composite structure.

This main frame structure I comprises, in this instance, vertical, spaced supporting columns or pedestals H and [2 which may be of hollow construction and are in this example, of generally rectangular cross section; a horizontally disposed bed or bench I4 extending across and between pedestals ll and I2 and providing by its upper side a horizontal bed or bench surface Ma; and a vertically disposed wall structure I 5 which is set back from the forward side of bed or table [4 and extended upwardly therefrom along and across the rear side thereof. The upper edge or top wall a of vertical wall structure l5 provides a horizontal, relatively narrow mounting,

base or supporting surf-ace extending across substantially the full width of the machine. This mounting base 15a is preferably provided with T-sloits l5b disposed longitudinally therealong.

General machine organization At an intermediate location on the top edge wall [5a of vertical wall structure 15, there is provided and mounted a work spindle head [5 in the form of a generally rectangular casing disposed transversely of wall structure 15 and being projected a distance forwardly therefrom above bed I ia. A power driven work and pattern spindle l! is mounted and journaled in horizontally disposed position extending through head l6, and generally longitudinally of the machine. The work spindle I1 is positioned in the forward portion of head [:6 with the inner or right hand end thereof being provided with and mounting a work holding chuck or the like fixture Ila, into which one end of a work piece or blank W to be machined may be secured in mounted position for revolution :by the spindle about a horizontal axis. The opposite, outer or left hand end of spindle I1 is provided with a suitable mounting fixture or holder [lb for attachment thereto in mounted position thereon, of a circular pattern or master cam M for rotation by spindle ll about the horizontal axis of revolution of the work piece W. Head l6 houses a suitable power drive to be hereinafter described, for rotating spindle I! from a motor SM which, in this example, is of the variable speed, shunt wound, D. C. type.

A saddle structure l8, referring to Figs. 5, 6, '7 and 8, is slid-ably mounted in vertically disposed position on the forward or front side of the vertical wall structure I5 below the spindle head IE but above bed 14, for movements longitudinally of the machine in either direction along a straight line path generally parallel with the axis of the work spindle IT. This saddle structure 18 is translated along its straight line path of movement from right to left on its feeding cycle, by a feed screw F driven from the spindle motor SM through a suitable power transmission or drive, as will be described hereinafter. The feeding movement of the saddle i8 is effected at a rate of linear feed which is in direct proportion to the rate of revolution of the Work piece W by the work spindle ll.

The movement of saddle l8 in the reverse direction, that is, from left to right relative to the machine in this instance, is effected at a rapid traverse rate by a separate and independent motor RTM located at the left hand end or the machine, through a drive transmission to be later described, and adapted to be engaged selectively either automatically or manually under the control of the operator with the saddle feed screw F. The rapid traverse drive transmission is associated and interlocked with mechanism for disconnecting the feed screw F from the feed drive driven from the spindle motor SM, before the rapid traverse drive is connected with feed screw F, and for disconnecting [the latter drive before the feed drive is connected.

A cutter and tracer cross feeding slide or carriage I9 is slidably mounted on and carried by the saddle structure 18. Carriage i9 is movable upwardly and downwardly, i. e. in or out to a work piece. on saddle structure 13 inde pendently thereof along and constrained to a straight line path radially disposed relative to the axis of revolution of the work piece W, and being .perpendicular to the path of horizontal feed and rapid traverse movements of the saddle structure 18. Thus, the carriage i9 is movable for cross feeding a cutter tool and tracer in and out radially relative to a work piece W and. a master cam M, respectively, and for feeding and rapid traverse movements as a unit with saddle l8, axially along the workpiece and master cam.

The cross feed carriage l9 thus mounted, is moved bodily laterally along the work piece and master cam with the saddle 1-8 on all longitudinal feed and rapid traverse movements of the latter. The carriage I9 mounts thereon at the right hand upper end portion thereof a self-contained power driven cutter spindle unit 29 which, in this instance, includes the cutter spindle 2|, an electric motor CM, and a suitable power transmission or drive 22 from the motor to the spindle.

The inner end of the cutter spindle 2! is adapted to mount thereon a circular cutting tool such, for example, as a circular milling cutter C having cutting teeth or cutting edges CT spaced around the periphery thereof.

At the opposite, left hand end of the cross feed carriage l9, there is mounted a tracer unit 23, which includes a circular tracer element or cam follower in the form of an idler roller T mounted and positioned opposite master cam M for rotation about an axis parallel with the axis of revolution of the cam M, by rolling contact with the cam as the latter is revolved.

The cutter spindle unit 20 and the tracer unit 23 are adjustably mounted and attached on cross feed carriage un it IQ for the required positioning thereof relative to each other to properly position the cutter C and the tracer T relative to a work p1ece W and master cam M, respectively.

A biasing means is provided acting continuously to yieldingly bias the cutter and tracer cross feed carriage unit l9 along its radial path of feed inwardly toward the master cam M and work piece W in order to position and engage the tracer roller T with cam M and the cutter C in cutting engagement with a work piece W. Such biasing means, in this example, is of the spring loading type embodying a pair of spring units 24 mounted and supported on and in position depending from the lower side of the saddle structure 18, with suitable force transmitting mechanism to be hereinafter described, operatively connecting units 24 with the cross feed carriage unit I9 for spring loading such carriage from the units 24.

A mechanism which may be automatically and/or manually controlled, is provided for retracting the cross feed carriage unit I9 from operative, spring biased position engaging tracer roller T and rotary cutter C with master cam M and work piece W, respectively, against the biasing forces exerted on the carriage by the spring loading units 24. In the machine organization of the present example, such retracting or pullback mechanism is constituted by a fluid pressure actuated cylinder and plunger unit 25 mounted and supported on and depending from the lower portion of the saddle structure I8, and a pressure fluid control valve unit 26 mounted at the right hand end of bed IA of frame structure I, for controlling either automatically or manually the cylinder and plunger unit 25.

In automatic cycling, the control valve unit 26 is caused to be operated to pull back or retract cross feed carriage I9 to withdrawn position relative to the master cam M and the work piece W, by the arrival of the saddle structure I8 at the end of its feed movement and prior to the rapid traverse of the saddle structure back to starting position for the next machining cycle. The control valve unit 26 also includes a hand lever 26A by which the valve may be manuall operated to effect pull back of the cutter and tracer cross feed carriage unit I9.

With the work piece W in mounted position in the revolving work holder of the spindle shaft, and a master cam M providing the peripheral contour surface therearound constituting an enlarged or blown-up and precise reproduction of the contours radially and axially of the portion of the work piece or blank W which it is desired to machine out to completed form, the machine organization is set for effecting such machining by releasing the cross feed carriage I9 to the action of the spring loading units 24, so that, the carriage is spring biased and forced thereby upwardly and inwardly at a controlled rate toward the master cam M and work piece W, until the tracer roller T is engaged and maintained yieldingly in engagement with the peripheral pattern surface m of the master cam. By properly adjusting the cutter spindle unit 20 of the cutter C thereof on the carriage I9 relative to the tracer unit 23 and its tracer roller T, the cutter C with the carriage unit IS in such spring biased position will be properly located for machining engagement with the work piece W for the start of the machining cycle.

The spindle motor SM is then placed in operation to revolve the work piece and simultaneously to rotate the feed screw F for feeding the saddle structure I8 and the tracer and cutter carriage I9, axially along the work piece W and the master cam M. As the master cam M is revolved with the tracer roller T spring biased yieldingly into engagement with the cam, the cross feed carriage I9 is moved inwardly toward and outwardly away from the work piece W as the tracer roller T follows the pattern surface of the revolving cam, being forced outwardly away from the work piece by portions of the cam surface of greater radius and being forced or biased inwardly by the spring loading from units 24, to follow and maintain sensing engagement with the portions of the cam surface of lesser radius.

An important and basic feature of the invention, resides in controlling automatically the rate of rotation of the work piece W and the rate of linear feed of the saddle structure I8, by the rate of movements either inwardly or outwardly of the cutter and tracer cross feed carriage I9, radially relative to the axis of revolution of the work piece. By this feature, as will be hereinafter explained in detail, when the cross feed carriage I9 is at rest, the motor SM is operated at its maximum speed setting to revolve the master cam M and the work piece W and to feed saddle structure I8 and the cross feed carriage I9 at maximum rates of rotation and linear feed, respectively. But upon movement of the cross feed carriage unit IS in either direction, that is, inwardly or outwardly, along its radial path of movement, the rate of speed of the motor SM is reduced to thereby reduce both the rate of revolution of work piece W and cam M and the rate of linear feed of the saddle structure I 8, in direct proportion to the rate of movement of the cross feed carriage.

In this example, such slow down control is effected through the medium of an electronic control system or network which is caused to function and control the rate of speed of the motor SM through the imposition. 0n the network of an electrical signal in th form of a potential or voltage of a magnitude dependent upon the rate of movement of the cross feed carriage. Such signal impulses are generated by a signal generator G which is actuated by the cross feeding movements of the carriage I9 to generate and impose on the electronic motor control network a signal in the form of an electrical potential or voltage of a magnitude in direct ratio to the rate of carriage movement at any instant, that is, the higher the rate of movement the greater the magnitude and the lower the rate of movement the lower the magnitude, of the electrical potential or voltage of the signal imposed on the electronic network.

Work and pattern spindle and drive therefor The work and pattern spindle I1, referring now to Figs. 2, 3 and 8, is in this particular example of general barrel or drum form having a low diameter to length ratio. Spindle I1 is mounted in horizontal position across and within the forward side of the head I6, with its opposite ends journaled in suitable antifriction bearing assemblies lie and H11 secured. in opposite side walls, respectively, of the casing forming the head I6. A worm wheel 30 is provided on and around spindle I1 adjacent the right hand end thereof withi head I6. The variable speed, direct current motor SM is mounted in position on and extended rearwardly from the rear of head I6 with the motor shaft 3| horizontally disposed with its axis generally perpendicular to the axis of work spindle The motor shaft 3|, or an extension thereof, is extended forwardly through head I6 across the upper side of and generally tangential to the worm wheel 30. Motor or power shaft 3 l' mounts on the forward end thereof a worm 32 in driving mesh with the worm wheel 30 of spindle I'I. Thus, operation of motor SM rotates the engaged worm 32 and worm wheel 30 to revolve the work spindle I1 at a rate of speed determined by the rate of rotation of motor SM and the gear ratio between worm 32 and worm wheel 30.

The motor SM is of the variable speed type and may be manually controlled for starting and stopping by the Start button 5 and the Stop button 6 located at the control push button sta- 9 tion 4 mounted on the upper side of the spindle head 16. Control buttons 5 and 6 are suitably connected in the control circuit for the motor SM, as will be clear by reference to Fig. 21.

Longitudinal feed and drive therefor The feed of the saddle and cross feed carriage unit I8l9, is effected through a suitable power transmission mechanism driven by the motor SM and driving the longitudinal feed screw F. This transmission feeds the carriage unit l8--l9 with cutter C and tracer roller T, axially along a work piece W and the master cam M, respectively, in a direction from right to left relative to the machine, in this example. Feed screw F is mounted in horizontally disposed position longitudinally of the machine at the forward side of the vertical wall structure 15 and extends across the rear side of saddle structure It, being operatively engaged therewith by a suitable feed screw nut unit FN. The feed screw F is supported and journaled adjacent its opposite ends in suitable antifriction bearings I50 and lEd, respectively, carried on or from adjacent portions of the vertical wall structure l5 of the machine frame. In this example, feed screw F is extended outwardly at its right hand end beyond the adjacent end of vertical wall structure 15 and mounts thereon a suitable hand wheel or crank FH for selective operation to manually operate the feed screw to move the saddle structure [8 either in a feed or in a rapid traverse direction.

The drive or power transmission from motor SM to the feed screw F comprises a system of shafts and gears, including a power input or drive shaft and a change speed gear train for selective setting to cause feeding rotation of the feed screw within a selected range of several ranges of feeding speeds. Such drive shaft 33, referring now to Figs. 2, 3 and 8, is mounted and journaled in vertically disposed position spaced to the rear of spindle l1 and extending a distance upwardly through and into the head 16. Shaft 33 extends downwardly from head [6 through an annular bearing holder 34 mounted in a vertical openin formed in the top wall l5a of vertical wall structure IS. A bearing sleeve 34a is mounted at its upper end in bearing carrier 34 and depends downwardly therefrom with its bore in axial alignment with the axis of shaft 33. Bearing sleeve 34a is received in and extends downwardly through a vertical bore formed in fixed structure 34b within the frame.

A bevel gear 35 is positioned in the bore in structure 341) between the lower end thereof and the lower end of bearing sleeve 34a. The bevel gear 35 is provided with an upwardly extended sleeve forming hub 35a which is journaled in the bearing sleeve 34a. The bevel gear 35 and its hub are formed with an axial bore therethrough having its surrounding wall longitudinally splined. The lower length of shaft 33 is provided with longitudinal splines 33a thereon and extends through the splined bore of bevel gear 35 in driving engagement with that gear.

The drive shaft 33 terminates in the upper portion of head [5 in a reduced diameter section 36 having thereon the longitudinal splines 35a. Splined section 36a extends upwardly through the splined axial bore of a worm wheel 3! and its upwardly extended hub forming bearing sleeve 3%, so that, drive shaft 33 is in driven relation with worm wheel 31. The hub forming sleeve 31a of worm wheel 31 is journaled in a set of anti-friction bearing assemblies 311) mounted in an annu- 10 lar wall formed by a flange 310 depending into the head 16 from the upper side thereof.

The worm wheel 31 is in driven engagement with a worm 31 On the motor drive shaft 3|. Hence, when motor SM is operatin to drive work spindle ll, the worm wheel 31 is simultaneously driven from the worm 31' to drive shaft 33 and the bevel gear 35 at the lower end thereof.

A bevel gear 38 having an extended sleeve forming hub 33a is mounted in horizontal position in a bearing 38b in structure 34b with the bevel gear 38 in driven engagement with bevel gear 35. A horizontal shaft 39 is mounted with its inner end extended into the hub 38a of bevel gear 38 in driven relation therewith. Shaft 39 extends horizontally and downwardly within wall structure [5 toward the left hand end of the machine, and at its outer end is supported and journaled in an anti-friction bearing assembly 39a mounted in vertically disposed fixed structure, such as the wall or plate member 391), within the vertical frame structure I5. At its outer end at the outer side of plate member 391), the shaft 39 mounts and has keyed thereto a pinion 40 in driven relation therewith.

. A change speed gear train is provided between and connecting driven pinion 40 with the feed screw F, through a feed clutch unit FC. This change speed gear train is of the two-speed type so as to give two (2) ranges of speed within which feed screw F may be driven by the variable speed motor SM.

Operating mechanism for the clutch F0 is provided and includes a manually operable rock shaft 60 mounted and journaled in the machine frame structure extending through the forward wall of a gear casing 6| which extends forwardly from frame structure I5 at the left hand end of the machine. Hand lever FCH is removably mounted in a socket member Bla secured on the exterior end of shaft 60 for rocking this shaft to cause operation of clutch FC to place motor SM in driving connection with feed screw F or out of driving connection with the feed screw.

A clutch actuator 58 is coupled by mechanism 60' with the inner end of shaft 60. Actuator 58 is also operable by a feed rod 62 which is mounted extending across the machine above bench IA. The left hand end of feed rod 62 is pivotally coupled with the end of a crank arm 63 on shaft 60. Feed rod 62 is mounted for movements axially in either direction by swinging of crank arm 63, or conversely, for movements in either direction by forces applied to the rod at the right hand end of the machine.

In this example, the clutch F0 is adapted to be actuated to position for driving feed screw F by manual operation of rock shaft 60, and to be actuated to position out of driving connection with feed screw F by either manual actuation of shaft 60 or automatically by energization of a solenoid FS.

Rapid traverse drive For rapid traversing the saddle and cross feed carriage l8l9, the feed screw F after being disconnected from the feed train, may then be driven from the rapid traverse motor RTM in a direction and at a rate to rapid traverse the saddle and carriage unit l8--| 9 to the right from itiis position at the conclusion of a feed cycle,

rough a drive mechani clutch unit RTC. sm which includes a Operating mechanism is provided for the clutch R'IC. This mechanism includes a manually operable rock shaft 18 mounted and journaled in the machine frame structure in position extend-. ing through the forward wall of gear casing 61. In this instance the rock shaft 18 is positioned parallel with but spaced downwardly and forwardly relative to the rock shaft 60 for the feed clutch FC. Socket member 18' is secured on the exterior end of shaft 18 for removably receiving a suitable hand lever for rocking the shaft.

A crank arm 19 is mounted on the inner end of rock shaft 18 and depends downwardly therefrom. A rapid traverse clutch control rod 80 is pivotally and slidably connected to the lower end of crank arm 19 by a pin 80a which is received in the vertically slotted, bifurcated end of the crank arm, as will be clear by reference to Figs. 3 and 4. Rod 80 extends from the crank arm 19 across the machine at the forward side of vertical wall structure I5 and immediately above the upper surface Ma of bench H, to the right hand end of the machine where the rod is suitably slidably journaled in an end wall of stricture 15. Thus rapid traverse clutch control rod 80 is mounted for movements axially in either direction by swinging or oscillation of crank arm 19, or conversely, is movable axially to swing that arm in either direction by forces applied to the rod acting axially thereof.

The rapid transverse clutch RTC is adapted to be engaged and disengaged automatically in the normal work piece machining cycle of the machine. The clutch is engaged automatically by energization of the rapid traverse clutch actuating solenoid HTS which, in this instance, is mounted within the casing 6| on the rear wall of vertical frame structure l5, as will be clear by reference to Figs. 4 and 4a.

The rapid traverse clutch RTC in the normal operating cycle of the machine is disengaged mechanically but automatically after engagement by the solenoid RTS, by actuation of the rapid traverse carriage control rod 80 from the saddle and carriage unit I8 -l 9.

Rapid traverse clutch RTC may also be selectively engaged and disengaged manually by the operator by rocking shaft 18 from a suitable hand lever such as lever FCH, inserted in the socket member 18'.

Saddle and cross feed carriage unit The saddle and carriage unit l8-I9 includes the. saddle I8 mounted for movements longitudinally of the machine parallel with the axis of the work spindle I1, and the cross feed carriage 19- mounted for movements on saddle l8 in a path perpendicular to the path of longitudinal movements of the saddle and disposed radially of the axis of rotation of the work spindle ll. The cross feed carriage l9 mounts thereon the tracer T and the rotary cutter C which are moved with the carriage simultaneously in a fixed relationship toward andfrom master cam M and a work piece W, respectively, along straight line paths disposed radially of and which in this instance pass through the common axis of rotation of the master cam M and a work piece W.

Referring to Figs. 3 to 8, in connection with Fig. 2 the saddle i8 is constituted by a body structure which may be in the form of a casting slidably mounted and constrained to straight line movements on vertically spaced, parallel and horizontal ways [8a provided on the forward side of the vertical wall structure l5 in locations thereon parallel with the axis of rotation of the work spindle H. The inner side of saddle I8 is provided with slide ways 18b in which the ways I: are received to slidably mount and confine the saddle in its operative position on frame structure I5. The forward side of saddle l8 pro? vides an upwardly and rearwardly (downwardly and outwardly) inclined forward surface or bed 180 which at its lower outer side terminates in an edge portion positioned spaced a distance forwardly of the vertical plane of the forward sides of pedestals H and I2 and bench 14. Thus mounted, the saddle I8 is horizontally slidable on ways I811 in either direction along a straight line path longitudinally of the machine to the right or left.

At its rear side the saddle I8 mounts the feed screw nut FN providing an internally threaded bore through which the feed screw F extends with the external threading thereof in engage ment with the internal threading of the feed nut FN. The feed screw F is located intermediate and within the space between ways I'Ba with the feed nut FN extended inwardly into the space between the ways in driven engagement with the feed screw.

The cross feed carriage I9 is constituted by a table forming structure mounted on the forward, inclined side of saddle l8 and having a length longitudinally of the machine considerably greater than the width of saddle I8, so as to provide for mounting thereon the tracer unit 23 and the powered cutter spindle unit 20- for operative positioning thereon relative to master cam M and the work piece W, respectively. Carriage i9 is preferably of such a length horizontally as to extend beyond the right hand end of vertical wall structure 15 when the saddle and carriage unit is at its limit of rapid traverse movement to the right in position for feeding into a work piece at the start of a machining cycle.

If desired, as in the example hereof, the right hand end section of carriage [9- may have bearing engagement with a bearing surface provided. on the adjacent portion of saddle l8 as indicated at We in Fig. 6.

Carriage I9 is mounted on the forwardly inclined bed provided by saddle l8 for movements upwardly or downwardly thereom that is, in orout relative to master cam M and a work piece W, along a path perpendicular to the path oflongitudinal movements of saddle H1 and radiallydisposed relative to the workpiece [1. The plane of the outer surface of the table structure provided by carriage I9, is generally parallel with the plane of the inclined forward surface of the saddle body, so that, forward surface of earriage I9 is disposed and movable, in an upwardly and rearwardly (downwardly and; forwardly) inclined plane disposed generally radially relative to work spindle ll.

In this example, carriage l9 is mounted on and constrained to such path of movements. by an arrangement of spaced, vertically disposed series of anti-friction balls l9a confined in rolling, minimum friction contact between pairs of rails or tracks I91) and I90, with the rail or track Nb of each pair mounted on and, movable with carriage l 9 and the opposite rail I of each pair fixed on saddle i 8, as will be clear by reference to Fig. 6. Thus mounted, cross feed carraige I9 is movable on and independently of saddle 3 for its cross feed movements in and out-j with minimum friction and constrained to the path of such movements by these spaced, anti-friction ball slide arrange" ents.

Cross feed carriage I9 is provided with the horizontal, vertically spaced T-slots l'9d in the.

13 front side thereof, by which the tracer unit 23 and the powered cutter spindle unit 20 may be adjustably mounted and positioned on the carriage.

Tracer unit and cutter spindle unit The tracer unit 23 includes a mounting frame structure or carrier having a base 23a secured in position adjusted longitudinally of carriage 19. by the attaching bolts 23b engaged in a T-slot [9d, and a frame 230 mounted on this base for adjustment horizontally and vertically of the base. The upper end of frame 230 has a tracer spindle mounting head 23d positioned thereon extending horizontally thereacross. The head 23d mounts and journals therein the horizontal tracer spindle 23c. Spindle 23c extends longitudinally through head 23d and mounts at the left hand, exterior end thereof the circular tracer roller T for rolling sensing engagement with the pattern surface in around the master cam M. The tracer mounting frame or carrier is preferably arranged for micrometer adjustments horizontally and vertically for set-up purposes.

The powered cutter spindle unit 20 includes a base 20a secured on the right hand end portion of carriage l9 by bolts 2% engaged in the T-slots |9d for adjustment of the position of the unit longitudinally of carriage l9. Bolts 2% are received in vertically disposed slots in the base which permit of adjusting the unit 20 vertically on carriage l9, this is, in or out relative to work spindle I! and a work piece W mounted therein.

A cutter spindle head 200 is provided in horizontally disposed position on and across the upper side of base 20a and mounts and journals therein a cutter spindle 2|. Spindle 2| extends through head 20c and provides at its left hand end for detachable mounting thereon of a suitable circular cutter, such as a rotary milling cutter C. The right hand end of cutter spindle 2| mounts thereon suitable belt pulleys 21a of different effective diameters, respectively.

On the base 20a below cutter head 200 there is mounted the cutter spindle drive motor CM as a component of the unit 20. Motor CM is positioned with its shaft 20d disposed horizontally. Motor shaft 20d mounts on its right hand end the pulleys Me of different effective diameters, respectively, for selective driving engagement with the pulleys 2la, of cutter spindle 2! by the belt 20 The arrangement and adjusted mounting of the tracer unit 23 and of the cutter spindle unit 20 relative to each other and relative to the master cam and a particular work piece W to be me.- chined, is such that the axes of rotation of the tracer roller T and of a cutter C on spindle 2|, lie in a radial plane passing through the common axis of rotation of the master cam and the work piece, such plane constituting the path of straight line in and out or cross feeding movements of the carriage l9 and being inclined forwardly and downwardly relative to a vertical plane.

As will be explained hereinafter, the width of the peripheral pattern surface m around the master cam M is the same as the length of that portion of a work piece W to be machined, so that, tracer unit 23 and cutter spindle unit 20 are mounted in an ad usted, horizontally spaced fixed relationship such that the tracer roller T will engage the right hand side or starting portion of pattern surface m at exactly the moment Cross feed carriage biasing mechanism In the machine of this example, the cross feed carriage I9 is spring biased upwardly, that is, inwardly, toward master cam M and a work piece W by the spring loading units 24. Referring to Fig. 8 in connection with Figs. 1, 2 and 5, each spring loading unit 24 embodies a cylindrical casing 24a mounted and supported at its upper end by a bracket or mounting structure 2422 from the lower forward side of saddle I8, in position depending downwardly from the saddle into position at the forward side of the machine. Two (2) such units are employed in this instance, mounted in position depending from the saddle l8, spaced equidistant from the vertical or media; center of the saddle (see Fig. 2).

Under the combined biasing forces of the two units 24, the carriage I9 is continuously spring biased upwardly to a position to engage tracer roller T with master cam M and to position cutter C for machining engagement with a work piece W. The biasing forces may be adjusted by adjusting the threaded stems Me to increase or decrease the compression of springs 241, as well as for adjustment relative to each other to equalize the biasing forces applied by these units to the carriage [9.

It is to be here noted that the cross feed carriage I9 is so mounted on and positioned by the forwardly inclined bed provided by saddle 18, that the carriage moves along and is constrained to a straight line path in a plane inclined at an angle forwardly and downwardly (rearwardly and upwardly) to the horizontal. In this particular example, such angle is of the order of approximately 70 to the horizontal, so that, the cross feed carriage is in effect canted or inclined at an angle of approximately the order of 20 from the vertical. By this arrangement and mounting of the cross feed carriage, the operational sensitivity of the carriage is increased, and hence, contact pressures required for accurate following are thereby reduced with resulting increase in precision and efficiency in operation.

Cross feed carriage "pull back mechanism In order to retract or pull back the cross feed carriage l9 downwardly to a position with the tracer roller T and the cutter C out of engagement with and clear of master cam M and a work piece W, for rapid traverse of the saddle and carriage unit I8!9 from its position at the end of the machining cycle to its position for the start of the next machining cycle, a carriage retracting or pull back mechanism is provided which in this example is of the air pressure actuated type. This pull back mechanism includes the air cylinder 25, a control valve 26 with a control lever 26A, and suitable air lines connected between the valve and the cylinder and connecting the valve with a source of air under pressure.

The air cylinder 25, referrin now to Figs. 1, 2 and 5 in particu ar. is mounted by a suitable b acket structure 25a to t e lo er forward portion of saddle structure it in position between spring loading units 24 andextending downwardly and forwardly from the saddle structure in general parallelism with the units 24. Cylinder 25 includes a piston 25b reciprocal therein and having a piston or actuating rod 250 extending upwardly and outwardly through a suitable sealing gland in which it is slidably received in the upper end head of cylinder 25. The upper end of this plunger 250 is connected to the lower edge portion of carriage body it as will be clear by reference to Fig. 5. Such connection may be efi'ected by threading the upper end of rod 250 into a tapped bore opening through the lower edge of carriage body l8, or in any other suitable manner.

Cylinder 25 is provided through the side wall adjacent the upper end thereof, with an inlet-- outlet port 255! for discharge of pressure fluid into the cylinder above piston 25b to force the piston downwardly in the cylinder, and for discharge of pressure fluid from the cylinder to relieve the pressure therein to permit of the piston being drawn upwardly in the cylinder under the action of the spring loading units 24 on carriage 19. Thus, by discharging pressure fluid through port 25d above piston 25?) the piston is forced downwardly to thereby retract or pull back carriage [9 against the biasing forces exerted thereon by units 24. When pressure fluid to the cylinder is out of! and port 250i is opened to atmosphere for releasing the pressure in the cylinder by exhausting therefrom the contained fluid, the spring biasing units 24 then take over and return carriage l9 upwardly to operatively position tracer roller T and the cutter C'.

In this instance the operation of pull back cylinder 25 is effected through the medium of the control valve 26.

Control valve 26 may be of any of the familiar three-way types suitable for the purpose.

Air cylinder control mice solenoid and feed clutch interlock The solenoid AS is provided for actuating automatically the control valve unit 26 from air cylinder exhausting position to position i or discharging air under pressure to the air cylinder 25. This solenoid AS is mounted in horizontally disposed position extending forwardly from a rear depending wall portion of a bracket and. housing structure 85, supported from the right hand side wall of frame structure it to the rear of valve unit 25 (see Fig. Solenoid AS includes an armature 86 projecting forwardly therefrom with its axis generally parallel with and in the same horizontal plane as the axis of the valve plunger 280 of valve unit 26 suitable mechanism is included operatively coupling the valve plunger with armature 86.

When the solenoid FS' is energized at the end of the feed cycle, the clutch is moved to position disconnecting iced screw F from the feed gear train from motor SM. Simultaneously with the encrgizati'on of solenoid FS, the control valve solenoid. AS is energized and forces valve plunger 26c outwardly to set the valve unit 25 for dis charge of air under pressure into the cylinder 25 to effect pull back of the carriage and saddle unit l.8l9.,

After the completion of the. rapid or return traverse and with the saddle and carriage unit l8-I9 in position for starting the next machining cycle, the operator may, after manually releasing the safety latch 28 by means of hand lever 29 to release feed carriage I9 (see Fig. 5), swing the control lever 26A to its intermediate position for throttled release of pressure from cylinder 25 to atmosphere to thus effect a controlled, slow, upward projection of the saddle and carriage unit to operative position for starting the next feed cycle.

Feed stop rodand feed limit switch The saddle l8 mounts a horizontally disposed feed stop rod 90 which is adjustably secured to the left hand side of the saddle and which projects a distance outwardly therefrom with its axis parallel with the path of feed and traverse movements of the saddle and carriage unit l8l 9.

Referring to Figs. 1, 2 and 7, this feed rod 90 has at its outer (left hand) end a conical head SI which provides a camming surface therearound, with the outer end of the head providing a flat abutment surface am for engaging a fixed stop member 92 secured in position on the right hand side wall of the casing 6|, in line with feed rod. 99, to stop feed movement of the carriage unit at a predetermined point.

A feed limit switch 9, which in this example may be considered to be of the well-known micro switch type, is mounted in position on vertical frame structure l5 adjacent the right hand side wall of casing 6|. Feed limit switch 9 includes a. spring loaded switch contact actuating pin 93 which projects forwardly into position in the path of the head 9| or feed rod 90 for engagement by the conical camming surface of that head. Feed.

limit switch 9 is of the normally open contact type and is closed by forcing the actuating pin 93 inwardly. Upon release of inward forcing pressure from pin 93, the switch restores automatically to circuit opening position.

During the feed cycle, as the saddle and carriage unit l8-|9. approaches the end of its feeding movement, the camming surface of the conical head 9| of feed rod 90. engages and forces limit switch 9 to circuit closing position in advance of the engagement of the abutment end 9la of head 9| with. the stop 92. As will be more fully explained hereinafter, closing of limit switch 5 sets into operation certain timing relays which, after a predetermined period of time, will effect energization of solenoid F8 to cause operation of slip clutch FC to disengage gear 51 from feed. train gear 46 and thus disconnect feed screw F from driven connection with the feed train.

Rapid traverse interlock switch An interlock switch l0, referring to Fig. 9 in particular, is mounted on frame structure at the right hand end of the machine in position adjacent and opposite the inner side of crank. arm 88. This switch I!) may be of the microswitch type familiar in the art, and is of the normally open contact type. switch l0 includes a spring loaded actuating pin 881) which projects outwardly from the outer side thereof and which on inward displacement closes the switch contacts and the circuit connected therewith. Upon release of inward acting pressure therefrom, actuating pin 88b springs outwardly to restore the switch to circuitopening position. An abutment member 880 is provided on crank arm 88 in position for engaging switch actuating pin 8% to close switch l0 when arm 88- .is swung to the left to the position which it takes when clutch F0 is moved to position disengaged from the feed gear train from motor SM. When lever 88 is swung to the right to its position with clutch lFC engaged with the feed train, abutment 88b s swung out of engagement with switch actuatmg pin 8% to permit the switch in to restore to circuit opening position. Interlock switch It 17- functions to close the energizing circuit to the rapid traverse clutch actuating solenoid RTS after that circuit has been set up and conditioned for closing by certain timing relays, as will be referred to hereinafter.

The master cam The master cam M and a work piece W mounted in the work holding fixture [la in the example machine hereof, are rotated about a'common horizontal axis provided by the Work spindle H, with the master cam controlling through the cam follower or tracer roller T, the cross feeding movements of the circular, rotary cutter C toward and from the work piece W, as the cutter is fed axially along the work piece, to cause the cutter to mill out precisely the required contours of the finished article as dictated and controlled by the pattern surface in of the master cam.

In accordance with my invention, 1 provide a master cam M having therearound the peripheral pattern surface m which has been generated from and is an expanded or enlarged contour surface of the required contour of the finished article to be machined from a work piece or blank. The contours radially along the Width of pattern surface m of master cam M correspond to and provide expanded reproductions of the contours radially of and angularly around the finished article, while the contours of the pattern surface m longitudinally or axially of the master cam at every location therearound are exact and precise expanded reproductions of the contours longitudinally or axially around the finished article. The width of the peripheral pattern surface m of master cam M is equal to the axial length of the portion of the work piece to be machined.

Referring to Fig. 10, I have designated schematically a cross section taken through a finished turbine blade WT of relatively flat, thin air foil section, the contours of which both radially and axially, are required to be reproduced in expanded or enlarged form radially and angularly therearound at the corresponding section or station on the master cam to be generated for use in machining from a work piece or blank W, the finished turbine blade WT. The contour of the corresponding cross section of the master cam M is shown surrounding and generated about the axis of revolution of the turbine blade WT, any desired or suitable method of generation having been utilized.

Thus, the contour surface m around the master cam M at the particular section illustrated, or at any section therethrough, is an enlarged or expanded contour radially of and angularly around the contour at the corresponding section or station or the relatively thin, generally rectangular air foil section of the turbine blade WT. It will be noted, for instance, that the contours angularly of the blade WT which sharply reverse in direction in following around the nose or leading edge portion WN thereof are flattened out and made less severe or sharp angularly, in the enlarged reproduction thereof at WN on the pattern surface m, while the very thin trailing edge portion WE which provides contours having extremely abrupt reversal in direction in following around the trailing edge, are expanded and made less severe or critical in the radially and angularly expanded reproduction WE thereof on the master cam pattern surface m. As the contours around the master cam M are formed or generated on radii of greater length than the radii of the corresponding contours on the turbine blade WT about the common axis of generation, the contours on the master cam are thus expanded angularly and are substantially smoothed out and made less severe around the pattern surface 111 of the master cam, so that, less severe or critical pressure angles will be presented between the cam follower or tracer roller T of the pattern surface m in following and maintaining efiicient and accurate sensing contact with and around the contours presented by the master cam pattern surface m.

In Fig. 10, the cam follower or tracer roller T is illustrated schematically in rolling, sensing contact with the master cam pattern surface m at a location thereon about to be forced to climb over and trace around the portion WE of the pattern surface which constitutes the radially and angularly expanded or enlarged contour corresponding precisely to the contour at and around the trailing edge portion WE of the turbine blade WT. The circular rotary cutter C is shown in its fixed relationship with the tracer roller T which is in milling or machining contact with the turbine blade WT at the precise location thereon corresponding to the location of roller T on the master cam pattern surface m. Thus, as the master cam M is rotated about the common axis of rotation of this cam and of the work piece W from which turbine blade WT is to be machined, the milling cutter C will be moved inwardly and outwardly radially relative to the work piece under the control of the tracer roller T as the latter is moved inwardly and outwardly, or will be at rest, as dictated by the high, low or concentric portions, respectively, presented by the enlarged or expanded blade contour presented by the pattern surface m of the master cam M.

A master cam M is generated for the contour of each particular article to be machined, and is removably mounted in the machine for rotation with the work piece about a common axis, by the work spindle l7 driven from motor SM. Thus, a master cam may be readily removed and replaced by a cam for controlling the machining of an article of different contour.

The master cam M, referring now to Figs. 1, 2, and 7, is mounted in position at the left hand side of head IS in driven relation with the work spindle l1 and a work piece W mounted in the work holder or fixture Ila. Cam M is secured on a suitable mandrel or arbor 96 and is mounted in operative position in the machine by attaching the cam and mandrel at the right hand side thereof to the work fixture [1b in driven connection therewith and by mounting and journaling the opposite, extended left hand end of the mandrel in a bearing provided at the outer end of a bearing hanger 97, which i adjustably secured on the upper side wall [5a of vertical wall structure l5, by suitable attaching bolts secured in a T slot l5b.

A work piece W from which the turbine blade WT of this example is to be machined, is removably secured rigidly held at its root end in the work holding fixture or chuck Na in position for rotation thereby on a common horizontal axis with the master cam M. A suitable dead center 98 may be provided for the outer tip end of the work piece W if desired or found necessary. The use of such dead center is dependent on the particular Work piece being machined. The dead center 98 is provided by a forwardly extended arm or hanger bracket removably secured for adjustment to the required position longitudinally 

